A cell repair strategy aimed at restoring neuronal function in neurodegenerative disease involves transplantation of neural stem cells either directly into the lesions, or into brain areas from which the grafted cells can migrate toward the desired anatomical destination. The success of this strategy depends on many factors, including the cellular and developmental properties of the neural stem cell/progenitor population used. Cells expressing the proteoglycan NG2 represent the largest population of mitotically active neural progenitors in the postnatal brain. In this proposal, we will isolate and transplant NG2-expressing cells from the (3-actin EYFP transgenic mouse, in which EYFP is uniformly expressed in all NG2+ cells throughout development. We have found that perinatal NG2+/EYFP+ progenitors isolated by fluorescence-activated cell sorting (FACS) are multipotential, i.e. can generate neurons, oligodendrocytes and astrocytes. FACS purified perinatal NG2+/EYFP+ progenitors grafted into the lateral ventricle (LV) of perinatal wild-type mice generate different subtypes of GABAergic intemeurons in distinct regions of the hippocampus, and oligodendrocytes in white matter and cerebral cortex. We propose to use the beta-actin-EYFP mice to establish a transplantation paradigm that will generate hippocampal inhibitory intemeurons from NG2+ progenitors purified from the subventricular zone and hippocampus of perinatal brains, and grafted into the brain of perinatal or adult mice. To study the cell and lineage potential of grafted NG2+ cells, we will employ a multidisciplinary approach, involving cellular, molecular and electrophysiological techniques, to define the phenotypes of hippocampal neuronal populations generated by NG2+ progenitors. By using patch-clamp recording techniques, we will determine whether the EYFP+ neurons derived from grafted NG2+/EYFP+ progenitors are synaptically integrated and display synaptic plasticity. Altogether, these studies will define a novel experimental paradigm aimed at repairing hippocampal GABAergic intemeuron damage in various pathological states, such as epilepsy, stroke, and ischemia